4th Class
Science
Matter and Materials
Matter

Matter

Gases are the substance in which the particles are very loosely packed and can compressed. Gases like LPG and CNG are compressed in cylinders and are used as fuels.

Any substance that has weight and occupies space is called matter. Matter exists in three states: solids, liquid and gases.

The molecules of solids are very closely packed with strong forces of attraction between them. They cannot move about freely.

Solids have fixed shapes and volumes.

The molecules in the liquid are loosely packed with weak forces of attraction. They move about more freely than in solids. Liquids have fixed volume but no fixed shape. They take up the shape of the container in which they are poured.

In gases the molecules are very loosely packed. They have very weak forces of attraction between them. Gases do not have fixed shape or volume. They occupy all the available space.

The different states of matter are interchangeable. When solids are heated they become liquids. When liquids are heated they become gases. When gases are cooled they become liquids, which upon further cooling become solids.